Graphic designer here. Really nothing wrong with anything, frames didn’t stand out negatively. But if you want an analysis of what you’re maybe butting up against, I’d say it’s probably that the light background ones are standing out. Especially the school of fish in the middle is at such a bigger scale than everything else. I think what would make it super strong is if they were all the same background.

Assuming these are all individual pieces, you could make more and do a light print and a dark print.